1. Field of the Invention
The present invention relates in general to secondary electrolytic cells, and more particularly, to lithium ion electrolytic cells, and associated electrolytic processes, having an additive which substantially precludes gas generation within the cell as a result of decomposition of solvents used in association with the electrolyte, and, wherein the additive itself does not form a gas during its decomposition during cell cycling and storage.
2. Background Art
Lithium ion electrolytic cells (such as lithium ion secondary batteries) have been known in the art for several years. Furthermore, lithium batteries using liquid, gel, polymer or plastic electrolytes which utilize carbon electrodes are likewise well known.
Although such electrolytes have been utilized, problems have been identified with respect to commercial solvents, utilized within the electrolyte, decomposing during cell cycling and storage. Indeed, as such solvents decompose, two adverse reactions occur. Specifically, upon initial charging of the cell, the solvent reacts with the electrode interface and forms a passivating layer thereat. As a result, the first cycle coulombic efficiency of the electrolytic cell is greatly diminished. Secondly, as the electrolytic cell is initially cycled and continues to be cycled, as well as stored, the solvent within the electrolyte continues to decompose--wherein such decomposition results in generation of gas, which creates a pressure buildup inside the cell.
In an attempt to resolve the above-identified problems, the prior art has utilized an additive, typically added to the solvent/electrolyte, which reacts with the surface of the electrode prior to the solvent. As a result, the additive forms a passivating layer which precludes decomposition of the solvent.
While such prior art electrolytic cells have addressed concerns relative to decomposition of the solvent, they nevertheless have been unable to resolve the adverse offset associated with gas generation due to decomposition of the additive itself. Accordingly, while the use of additives have proven somewhat beneficial, gas generation, albeit from the additives as opposed to the solvent, still persists.